【摘要】 为考察并掌握典型平原地区生活垃圾焚烧厂周边土壤中重金属Cd、Cr、Cu、Pb、Ni和Zn的污染现状,以上海市某生活垃圾焚烧厂为例,研究其周边土壤中重金属赋存形态分布特征及生物有效性,采用Tessier连续提取法结合电感耦合等离子体发射光谱检测分析表层土壤中目标重金属总量及形态分布,并利用风险评估编码法(RAC)评价其生态风险水平.结果表明:研究区域土壤中Pb和Zn主要以Fe-Mn氧化物结合态和残渣态为主(>80%); Cr、Cu和Ni则以残渣态为主(>60%); Cd虽以残渣态为主(>50%),但与其他重金属相比,其碳酸盐结合态占比相对较高.生物有效性分析结果显示,Cr、Cu和Ni以惰性态为主,生物有效性低,而潜在可利用态Cd、Pb和Zn占比较高,存在较高的释放风险.土壤中各重金属潜在生态风险水平由高到低依次为Cd>Zn>Pb>Cu>Ni>Cr,其中,Cu、Pb和Zn处于低风险水平,Cr和Ni处于无风险水平,而Cd处于中等风险水平.研究显示,该垃圾焚烧厂周边土壤中重金属已存在不同程度的污染累积,其中,潜在可利用态Cd的占比较高,已达中等风险水平,应引起重视.更多还原

【Abstract】 In order to investigate the pollution status,chemical species and bioavailability of Cd,Cr,Cu,Pb,Ni and Zn in the surface soils surrounding municipal solid waste incineration( MSWI) plants in the typical plain area,a MSWI located in Shanghai was taken as an example and the Tessier sequential extraction method with inductively coupled plasma-optical emission spectroscopy were used to analyze the total amount and species distribution of the heavy metals. The ecological risks of the heavy metals were assessed with the risk assessment code( RAC) method. The results showed that Pb and Zn were mostly bound to the Fe-Mn oxides and residual fractions( >80%),while Cr,Cu and Ni primarily existed in the residual fractions( >60%). By contrast,Cd was mainly in residual fractions( >50%),but a relatively high portion was bound to the carbonates compared with other heavy metals. The bioavailability analysis indicated that Cr,Cu and Ni remained in inert state with low bioavailability,whereas Cd,Pb and Zn had a high level of potential bioavailability with a high release risk. The potential ecological risks of these heavy metals were ranked in the order of Cd>Zn>Pb>Cu>Ni>Cr,in which Cr and Ni presented no any risk,while Cu,Pb and Zn had a low risk. However,Cd was found to have a moderate-level of risk. This study revealed that different degrees of heavy metal accumulation occurred in the vicinity of this MSWI plant. Cd had a relatively high level of potential bioavailability and reached a medium risk,which should be paid attention to.更多还原